Method and device for fine blanking and forming a workpiece

ABSTRACT

The invention relates to a device and a method for fine blanking and forming a workpiece out of a flat strip. 
     The invention has the task to provide a method and a device for fine blanking of small to medium sized parts which make it possible to massively save valuable materials, to combine the machining function of the active elements with the transportation function from one machining stage to the following machining stage increasing at the same time the quantity of strokes and the efficiency and to avoid stoppages of the production process caused by not removed from the tool waste. 
     This task is solved in the manner that the cutting plate ( 13 ) is formed as disc-shaped transfer part with several adapted to the effective elements cutting openings ( 20 ), which take up and clamp a cut out blank ( 8 ) to transport it from one machining stage to the next, wherein the transfer part is turnable with regard to the effective elements of the upper part ( 1 ) around a virtual axis (A) parallel to the machining direction in the center of the transfer part, turnable perpendicular to it after a lift over the effective elements ( 5, 17 ) of the lower part, and the cutting openings ( 20 ) in the transfer part are arranged on a common base circle (GK) the radius (R) of which coincides with the distance oft the machining stage to the axis (A), and that the machining stages of the upper part are arranged on the base circle (GK) at fix distances to each other, wherein the machining stages in the transfer part are allocated at least two diametrically opposed at the circumference, fixed in the pressure pad ( 3 ) of the upper part, arranged parallel to the axis (A) locking bolts ( 10 ) and several arranged diametrically opposed at the circumference locking openings ( 23 ) in the transfer part for adjusting, fixing and lining up the effective elements to each other.

The invention relates to a device for fine blanking and forming aworkpiece from a flat strip with several machining steps comprisingeffective elements like punches and/or forming element pressure pad forthe shearing and/or forming element, arranged at the pressure padV-shaped projections and pressure plate of an upper part and cuttingdie, ejector, coining anvil and pressure plate of a lower part in onemachining cycle consisting of blanking, stamping, preforming and/orpunching or the like, wherein the flat strip (6)is clamped between theclosed upper and lower parts and movable in feeding direction (Z) in theopen state of upper and lower parts.

The invention further relates to a method for fine blanking and forminga workpiece from a flat strip, wherein the flat strip is submitted toseveral successive machining steps comprising effective elements likeshearing punch and/or forming element, pressure pad, arranged at thepressure pad V-shaped projections and pressure plate of an upper partand cutting die, ejector, coining stamp and pressure plate of a lowerpart of a machining cycle consisting of blanking, stamping, preformingand/or punching or the like, wherein the flat strip is clamped betweenthe closed upper and lower parts to be machined and is sequentiallymoved forward in the open state of upper and lower parts.

STATE OF THE ART

Fine blanked parts with formed functional areas are mostly produced inprogressive tools comprising several sequential steps in progressivetools. In this process a cut out blank is taken up by a cross slide andled to the next machining stage when the tool is open.

From DE 21 65 224 A1 is known a device for continuous blanking amultitude of identical workpieces out of a metal sheet, strip or thelike in a multiple die press, which are interlocked into each other forthe optimum utilization of the material, wherein a blanking stand isarranged to house a shearing punch and a correspondingly formeddie-plate, which together form a cutting or blanking tool. Shearingpunch and die-plate are connected to each other via mechanical elements,which after every cutting operation, advantageously when the press ramcrosses the upper dead center, independently cause a synchronoushorizontal 180° turn of shearing punch and die-plate. This is realizedby executing half of the turning movement during the ascending anddescending strokes of the press rams, respectively. The target of thisturning movement is to get a material saving interlocking of the blanks.

Further from DE 44 09 658 A1 is known a tool combination for blankingmachines, especially for different machining of window and door casementsections or the like, wherein each tool has a die-plate and a punchingelement driven by the punching machine and the respective application ofthe tools is restrictedly guided by the punching machine. The die-platesof the tools are connected to a complex construction unit and rotatablesupported on an axis, which coincides with the direction of the movementof the punching machine drive. The respective punching elements alsoform a construction unit. Between the construction units is provided aneffective guidance that secures respectively uniform turning positionsand allows for approach and retreat of the construction units.

Despite of all the measures according to the state of the art have to beprovided material consuming excessive dimensions at designing the metalblank development, especially in case of smaller parts producedaccording to a multiple cut concept, to avoid an influence of theforming operations on the geometry of the pressed screen. After all incase of small parts per stroke emerge waste costs which are higher thanthe costs of the parts because fine blanking of certain sections ofparts consumes too big quantities of material.

A further disadvantage is that due to transporting the blanked parts bymeans of a cross slide the tool has to be opened, so that the crossslide can transport the blanked part to the next machining stage. Due tothis the specific production time per part is increasing. Furthermore,the rams of the press have to nearly go to their ascending or descendingdead centers what is limiting the quantity of strokes. Often left or nottaken out by the cross slide slugs in the tool area lead to additionalstoppages of the production process and to damages at workpieces.

TASK

At this state of the art the invention has the task to provide a methodand a device for fine blanking of small to medium sized parts which makeit possible to massively save valuable materials, to combine themachining function of the active elements with the transportationfunction from one machining stage to the following machining stageincreasing at the same time the quantity of strokes and the efficiencyand to avoid stoppages of the production process caused by not removedfrom the tool waste.

This task is solved by a device of the above mentioned kind with thecharacterizing elements of claim 1 an by a method with thecharacterizing elements of claim 12.

Advantageous aspects of the device and the method can be learned fromthe subclaims.

The solution according to this invention is characterized in that thecutting die takes over the effective function, i.e. is active element ofthe cutting and/or forming process, as well as the transfer function fortransporting the parts from machining stage to machining stage. That iswhy the cutting plate is formed as disc-shaped transfer part withseveral adapted to the effective elements process openings, which takeup and clamp the blanked workpiece or slug to transport it from onemachining stage to the next, wherein the transfer part is turnable withregard to the effective elements of the upper part around a virtual axisparallel to the machining direction in the center of the transfer part,turnable perpendicular to it after a lift over the effective elements ofthe lower part, and the process openings in the transfer part arearranged on a common base circle coinciding with the distance oft themachining stage to the axis, and that the machining elements of theupper part are arranged on the base circle at fix distances to eachother, wherein the machining stages in the transfer part are allocatedat least two diametrically opposed at the circumference, fixed in thepressure pad of the upper part, arranged perpendicular to the axislocking bolts and several arranged diametrically opposed at thecircumference locking bolt openings for adjusting, fixing and lining upthe effective elements to each other.

The transfer part for executing of the lifting and turning movements onthe one hand has a guiding element fixed in a mounting arranged on thepressure pad for vertically moving the transfer part in the directiontowards the locking bolt axis against the pressure pad and on the otherhand a turnable supported pivot in the thrust piece for turning thetransfer part.

The lifting movement of the transfer part is advantageously carried outhydraulically via the thrust piece by the studs pressing the guidingelement in the direction of the locking bolt axis.

The turning movement of the transfer part starts when the liftingmovement is finished and the effective elements of the lower part do notdisturb the turning movement of the cutting die any more.

So that the locking bolts can engage the locking openings during lockingupper part and lower part, i.e. arresting and positioning the transferpart, the axis of locking bolt and locking opening lie on a common line.

The device according to this invention makes it possible besidescarrying out one single machining cycle to alternatively also carry outthe machining stages of several machining cycles on base circlesconcentrically arranged with respect to the virtual rotation axis of thetransfer part. This leads to a significant increase in the quantity offabricated workpieces.

The feeding and outlet direction of the flat strip exceeds through thevirtual rotation axis of the transfer part, i.e. through the center ofthe base circle. Every machining cycle is allocated at least one outletchannel which depending on the quantity of machining stages leads to theoutside.

The slugs are removed to the outside via at least one outlet channel.The removal preferably is realized by means of blowing out in outsidedirection or band transport. Removing the slugs separately has theadvantage that the outlet of the finished workpieces is totallyseparated from waste removal. Thus the danger of a production stoppagedue to not removed slugs is largely excluded.

The method according to this invention allows that the workpiece and/orthe blank cut out of the flat strip is received and clamped in a processopening lying on a circuit and that it is stored in the process opening.By a lift movement with following rotation movement by an amount whichcoincides with the distance of the effective elements to each other theworkpiece stored in the respective process opening stepwise reaches thenext following machining stage, wherein during every turning step theeffective elements of the upper part and the effective elements of thelower part are brought to coincidence and after having been adjusted andclosed complete each other to a pair of effective elements of therespective machining stage.

The method according to this invention has the great advantage thatseveral machining cycles can be carried out at the same time, wherein afirst machining cycle is realized on a first base circle and a furthermachining cycle is realized on a base circle which is different from thefirst base circle.

Further it is a special advantage that a separate transport of the fineblanked and formed parts within the tool by means of a cross slide isnot required any more. The cutting die beside its active function alsotakes over the transport function. The workpieces are completely cut outand separated from the pressed screen, so that material wasting re-cutsdo not have to be accepted any more, especially in connection with smallparts. This leads to significant savings of material in the case ofsmall and medium sized fine blanking parts, whereby the application offine blanking stays lucrative despite of significantly rising steelprices.

That the fine blanked and formed workpieces after cutting or formingoperation are received and clamped in the process openings andtransported to the next machining stage brings the advantage that theworkpieces during the fine blanking or forming process can not bedamaged any more by possibly left in the tool area slugs.

Due to the transfer of the workpieces by means of the cutting die andthe elimination of a separate slide for transporting the parts the ramstroke of the press as a whole can be significantly reduced what makesit possible to significantly increase the quantity of strokes, i.e. thequantity of cycles.

Further advantages, characteristics and details accrue from thefollowing description with reference to the attached drawings.

EMBODIMENT

In the following the invention will be explained in more detail at theexample of an embodiment.

It is shown in

FIG. 1 a cross-section through the device according to this invention inthe open state of upper and lower parts along line A-A of FIG. 2,

FIG. 2 a top view of the device according to this invention according toFIG. 1,

FIG. 3 a section through the device according to this invention in themachining stage “cutting” in the upper dead center according to themethod of this invention,

FIG. 4 a section through the device according to this invention in themachining stage “coining” in the upper dead center according to themethod of this invention and

FIG. 5 a section through the device according to this invention in themachining step “ejecting” in the upper dead center according to themethod of this invention.

FIG. 1 shows the principle structure of the device according to thisinvention for producing a fine blanked and formed workpiece W.

The device according to this invention has an upper part 1 and a lowerpart 2. The upper part 1 of the device according to this inventioncomprises a pressure pad 3 with V-shaped projection 4, a punch 5 forpunching a flat strip 6, a shearing punch 7 for cutting out a punchedblank 8 from the flat strip 6, a coining die 9 (se FIG. 4) for carryingout a coining operation at the cut out blank 8 and at least two lockingbolts 10. The active elements punch 5, shearing punch 7 and coiningpunch 9 are guided in the pressure pad 3. Their respective workingdirection is perpendicular to the flat strip 6. The two locking bolts 10are arranged near the outer edge of the pressure pad 3 and arediametrically opposed to each other.The upper stud 11 under hydraulic pressure presses on the pressure pad3.

The lower part 2 consists of a mounting 12, a disk-shaped cutting die 13with guiding element 14, a waste channel 15, an ejector 16, a coininganvil 17 and a central journal 18 fixed on the lower pressure plate 19.Cutting die 13 and guiding element 14 form a common construction elementwhich is turnable. In the cutting die 13 are provided respective cuttingopenings 20 which are allocated the active elements 5, 7 and 9,respectively.

The cutting die 13 with its guiding element 14 is supported in thecenter of the journal 18.The guiding element 14 with its outer circumference supports on themounting 12, in plane E between the guiding surfaces of mounting 12 andguiding element 14 acts a not shown driving element, for example astepping motor for creating the necessary drive moment for rotating thecutting die 13 around its virtual axis A on the axis of the journal 18.

On the guiding element 14 under hydraulic pressure acts a stud 21, withthe help of which the cutting die 13 together with its guiding element14 can carry out a determined stroke movement perpendicular to the flatstrip 6. The ejector 16 as holder-up of the shearing punch 7 issupported by a further stud 22 under hydraulic pressure.

In the disk-shaped cutting die 13 near its outer circumference arearranged several locking openings 23, lying diametrically opposite toeach other. In closed lining up of upper and lower parts 1 respectively2 the two locking bolts 10 lying diametrically opposite to each otherrespectively engage two locking openings 23. The central axis of therespective locking opening 23 lies on the axis line B of locking bolt10. The locking openings 23 in this case are distributed along thecircumference of the cutting die 13 in such a way that in case of theengagement of the locking bolts 10 the respective effective elements ofupper and lower parts 1 respectively 2 together can form a pair ofeffective elements, i.e. one machining stage, respectively. The flatstrip 6 in the closed state of upper and lower parts is clamped betweenpressure pad 3 and cutting die 13 and the V-shaped projection 4 hasalready penetrated the flat strip 6.

The punch 5 and the respective cutting opening 20 of the cutting die 13,shearing punch 7 in the upper part 1 and ejector 16 in the lower part 2as well as coining stamp 9 in the upper part 1 and coining anvil 18 inthe lower part 2 form respective pairs of effective elements lying on acommon base circle GK, as is in the following described in detail inFIG. 2, the center of which is the virtual axis A.

FIG. 2 shows a top view of the device according to this inventionillustrating the operational process of the method according to thisinvention.

In the first processing step I the blank 8, possibly also an inner form,is cut out from the row of parts T1 of the flat strip 6 into the processopening 20 of cutting die 13 and not ejected. Blank 8 stays in theprocess opening 20. During the opening of upper part 1 and lower part 2of the device according to this invention the cutting die 13 togetherwith guiding element 14 is lifted by the hydraulically operated studs 21and with the blank 8 in the cutting opening 20 turned into the nextfollowing process position. In the example shown here the rotationalmovement is carried out clockwise to the rear side of the device. Ofcourse it is also part of this invention when the rotation direction isanti-clockwise.In the second processing step II upper and lower parts 1 respectively 2are closed, whereby the locking bolts 10 engage the respective lockingopenings 23 of cutting die 13. The cutting die 13 now is fixed by thelocking bolts 10 and the blank 8 can undergo the next followingprocessing operation, for example coining or ejecting the slugs 26 intoa channel 15 (see FIG. 1).In the third processing step III the cutting die 13 again with thestaying in the process opening 20 blank 8 during opening of upper andlower parts is lifted and turned until the next following processposition (processing stage) is reached. The cutting die 13, is, asdescribed already in the second processing step, fixed and upper andlower parts are closed. The respective process operation is carried out,wherein the process steps are repeated until machining of the part isfinished.In the fourth processing step IV the finished workpiece is ejected fromthe cutting opening 20 of cutting die 13 into a channel 25 and removedfrom the inner space of upper and lower parts for example by blowing itout. After opening upper and lower parts 1 respectively 2, lifting andturning of cutting die 13 the now free cutting opening 20 in the cuttingdie 13 reaches the process position in the row of parts T2 of flat strip6, so that a new machining cycle can be carried out clockwise on thefront side of the device.

The feeding direction Z of the flat strip 6 into the device according tothis invention exceeds over the center, i.e. along the virtual axis A,so that it is readily possible to apply flat strips 6 with differentwidths, when the base circle GK is respectively adjusted to thearrangement of the single machining stages.

According to the number of necessary machining cycles the single pairsof effective elements can lie on concentrically to each other arrangedbase circles GK, which respectively have different from the virtualrotation axis A of cutting die 13 radii R, so that several processingoperations can be carried out simultaneously.

Each machining cycle is allocated a channel 25 for transporting thefinished workpieces outside. The outlet direction AR of the finishedparts can vary according to the quantity of pairs of effective elements(machining stages). Thus the angles α with regard to the feedingdirection of the flat strip 6 may vary.

The channel 24 for removing of the slugs exceeds perpendicular to thefeeding directions of the flat strip 6 and thus is completely separatedfrom the removal of the finished parts, so that respective malfunctionscaused by left in the tool area slug rests are excluded.

The FIG. 3 to 5 illustrate the processing steps cutting, coining andejecting. In FIG. 3 upper part 1 and lower part 2 are closed and theflat strip 6 is clamped between pressure pad 3 and mounting 12. Thelocking bolt 10 is engaged in locking opening 23. The cutting die 13 isfixed. The punch 5 and the shearing punch 7 have cut respective partsinto to the process opening 20 of the cutting die 13.

FIG. 4 shows the processing operation coining. Upper part 1 and lowerpart 2 of the device according to this invention are closed and thecutting die 13 is fixed by the locking bolt 10. The coining stamp 9 andthe coining anvil 17 are in working position.In FIG. 5 is shown the ejection of finished fine blanked and formedworkpieces. A finished part is ejected into channel 25 and for examplecan be blown outside.

LIST OF REFERENCE SIGNS

-   upper part 1-   lower part 2-   pressure pad 3-   V-shaped projection 4-   punch 5-   flat strip 6-   shearing punch 7-   blank 8-   coining stamp 9-   locking bolt 10-   upper stud 11-   mounting 12-   cutting die (die-plate) 13-   guiding element 14-   waste channel 15-   ejector 16-   coining anvil 17-   journal 18-   lower pressure plate 19-   cutting openings in 13 20-   lower stud 21-   lower stud for 16 22-   locking openings 23-   outlet channel for finished parts 24, 25-   slugs 26-   virtual rotation axis A-   removal direction for finished parts AR-   axis line of 10 B-   base circle GK-   radius of GK R-   first row of parts on 6 T1-   second row of parts on 6 T2-   workpiece W-   feeding direction, forward direction of 6 Z-   angle of the removal direction of finished parts α-   process steps/machining stages I, II,III, IV

1. Device for fine blanking and forming a workpiece from a flat stripwith several machining steps comprising effective elements like punches(5, 7) and/or forming element (9), pressure pad (3) for the shearingand/or forming element, arranged at the pressure pad V-shapedprojections (4) and pressure plate of an upper part (1) and cutting die(13), ejector (16), coining anvil (17) and pressure plate of a lowerpart (2) in one machining cycle consisting of blanking, stamping,preforming and/or punching or the like, wherein the flat strip (6) isclamped between the closed upper and lower parts and movable in feedingdirection (Z) in the open state of upper and lower parts, characterizedin that the cutting plate (13) is formed as disc-shaped transfer partwith several adapted to the effective elements cutting openings (20),which take up and clamp a cut out blank (8) to transport it from onemachining stage to the next, wherein the transfer part is turnable withregard to the effective elements of the upper part (1) around a virtualaxis (A) parallel to the machining direction in the center of thetransfer part, turnable perpendicular to it after a lift over theeffective elements (5, 17) of the lower part, and the cutting openings(20) in the transfer part are arranged on a common base circle (GK) theradius (R) of which coincides with the distance of the machining stageto the axis (A), and that the machining stages of the upper part arearranged on the base circle (GK) at fix distances to each other, whereinthe machining stages in the transfer part are allocated at least twodiametrically opposed at the circumference, fixed in the pressure pad(3) of the upper part, arranged parallel to the axis (A) locking bolts(10) and several arranged diametrically opposed at the circumferencelocking openings (23) in the transfer part for adjusting, fixing andlining up the effective elements to each5 other.
 2. Device according toclaim 1, characterized in that the transfer part has a guiding element(14) hold in a mounting (12) arranged on the pressure plate (19) forvertically moving the transfer part in the direction of the axis (B) ofthe locking bolts against the pressure pad (3) and a journal (18) fixedat the stud ( ), wherein the transfer part is turnable around thejournal (18).
 3. Device according to claim 1, characterized in that thecutting die (13) and guiding element (14) form a common constructionunit.
 4. Device according to claim 1, characterized in that that theguiding element (14) is allocated a stepping motor engaging in plane Ebetween mounting (12) and guiding element (14) at the outercircumference of the guiding element (14) to turn the transfer part frommachining stage to machining stage.
 5. Device according to claim 1,characterized in that the axis of locking bolt (10) and locking opening(23) in the closed state of upper and lower parts (1, 2) are arranged onone common line (B).
 6. Device according to claim 1, characterized inthat all machining stages of one machining cycle are arranged on thebase circle (GK).
 7. Device according to claim 1, characterized in thatthe machining stages of several machining cycles are arranged onconcentrically lying to each other base circles (GK), which haverespectively different distances from the axis (A) of the transfer part.8. Device according to claim 1, characterized in that the feeding andoutlet direction (Z, AR) of the flat strip (6) exceeds over the centerof the base circle (GK).
 9. Device according to claim 1, characterizedin that at least one outlet channel (24) is provided for finishedworkpieces the direction of which with regard to the outlet direction(AR) of the flat strip (6) is variable.
 10. Device according to claim 1,characterized in that at least one outlet channel (25) is provided forfinished workpieces the direction of which with regard to the feedingdirection (ZR) of the flat strip (6) is variable.
 11. Device accordingto claim 1, characterized in that at least one outlet channel (15) isprovided for slugs.
 12. Method for fine blanking and forming a workpiecefrom a flat strip, wherein the flat strip is subjected to severalconsisting of effective elements like shearing punch and/or formingelement, pressure pad, arranged on the pressure pad V-shaped projectionsand pressure plate of an upper part and cutting die, ejector, coininganvil and pressure plate of a lower part sequential machining stages ofa machining cycle comprising cutting, coining, preforming and/orpunching or the like, the flat strip is clamped between closed upper andlower parts when machined and step by step moved on in the feedingdirection in the open state of upper and lower parts, characterized inthat the cut out workpiece and/or blank is received and clamped orstored in a cutting opening lying on a circuit of the cutting die and bya lift movement with following rotation movement of the cutting die byan amount which coincides with the distance of the effective elements toeach other step by step is fed to the effective elements of the upperpart lying on a circuit, wherein during every turning step the effectiveelements of the upper part and the effective elements of the lower partare brought to coincidence and after having been lined up and closedcomplete each other to a pair of effective elements of the respectivemachining stage.
 13. Method according to claim 12, characterized in thatthe movement along the circuit of the process openings in the cuttingdie and the movement along the circuit of the effective elements of theupper part are carried out on a common base circle.
 14. Method accordingto claim 12, characterized by the following sequentially carried outprocess steps: I) Cutting out the blank into the process opening of thecutting die and its remaining in the process opening with upper andlower parts closed with following lift of the cutting die over theeffective elements of the lower part and stepwise turning of therespective process opening of the cutting die to the next followingmachining stage with upper and lower parts open, II) Lining up andfixing of the effective elements during closing upper and lower partsand carrying out a next forming operation, III) carrying out the processaccording to steps I and II again, wherein these are repeated until themachining of the part is finished, IV) Ejecting and blowing out thefinished part with upper and lower parts open, wherein the cutting dieafter the lift movement is turned until the process opening of the freemachining stage is reached for carrying out a new machining cycle. 15.Method according to claim 12, characterized in that several machiningcycles can be carried out simultaneously, wherein a first machiningcycle is carried out on a first base circle and a further machiningcycle is carried out on a further base circle the radius of which isdifferent from that of the first base circle.
 16. Method according toclaim 12, characterized in that 20 the flat strip is led over the centerof the base circle.
 17. Method according to claim 12, characterized inthat the finished workpieces are removed from the opened upper and lowerparts by blowing out or band transport.
 18. Method according to claim11, characterized in that the slugs are removed from the closed upperand lower parts by blowing out or band transport.